a person who has achieved distinction and honor in some field
"he is one of the greats of American music"
A person of major significance, accomplishment or acclaim.
"Many historians consider Marie Curie a great scientist whose discoveries transformed modern medicine and physics."
In plain English: In this context, great is not a noun but an adjective used to describe something that is very good or impressive.
"The crowd cheered when the great appeared on stage to greet them."
Usage: Use "great" as a noun only in formal contexts to describe a historically significant figure, such as calling someone a "great" when their achievements are universally recognized. Avoid using it casually for any impressive person, as that usage often sounds hyperbolic rather than descriptive of major significance.
relatively large in size or number or extent; larger than others of its kind
"a great juicy steak"
"a great multitude"
"the great auk"
"a great old oak"
"a great ocean liner"
"a great delay"
of major significance or importance
"a great work of art"
"Einstein was one of the outstanding figures of the 20th centurey"
remarkable or out of the ordinary in degree or magnitude or effect
"a great crisis"
"had a great stake in the outcome"
Relatively large in scale, size, extent, number (i.e. having many parts or members) or duration (i.e. relatively long); very big.
"The great wall of China stretches across the landscape for thousands of miles."
In plain English: Great means really good or excellent.
"We had a great time at the beach yesterday."
Usage: Use "great" to describe something that is physically large in scale, size, or duration, such as a great distance or a great crowd. Avoid using it for general approval or excellence when you specifically mean magnitude rather than quality.
Very well (in a very satisfactory manner).
"The team executed the final play great, securing the victory in extra time."
In plain English: Great means very well or extremely good when used as an adverb.
"The car drove great in the heavy rain."
Usage: Use "great" as an adverb only in informal speech to mean "very well," such as when stating that something went great or you did great on a test. Avoid using it in formal writing where "well" is the standard and preferred choice for describing how an action was performed.
Expression of gladness and content about something.
"I'm just great now that we finally solved the mystery together."
The word "great" comes from Old English, where it originally meant big, thick, or massive. It traveled into modern English with this same sense of large size and weight.